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\(=\dfrac{19}{33}.\left(\dfrac{4}{21}+\dfrac{25}{42}\right)\)
\(=\dfrac{19}{33}.\dfrac{33}{42}\)
\(=\dfrac{19}{42}\)
Lời giải:
$=\frac{19}{33}\times (\frac{4}{21}+\frac{25}{42})$
$=\frac{19}{33}\times (\frac{8}{42}+\frac{25}{42})$
$=\frac{19}{33}\times \frac{33}{42}=\frac{19}{42}$
![](https://rs.olm.vn/images/avt/0.png?1311)
mọi người em đang cần gấp trả lời ạ
ai giúp được em xin cảm ơn ạ
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(\dfrac{5}{3}\cdot\dfrac{7}{10}=\dfrac{5}{10}\cdot\dfrac{7}{3}=\dfrac{14}{3}>2\)
\(\dfrac{5}{7}:\dfrac{7}{10}=\dfrac{5}{7}\cdot\dfrac{10}{7}=\dfrac{50}{49}< 2\)
=>\(\dfrac{5}{3}\cdot\dfrac{7}{10}>\dfrac{5}{7}:\dfrac{7}{10}\)
b: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(\dfrac{8}{9}:\dfrac{4}{3}=\dfrac{8}{9}\cdot\dfrac{3}{4}=\dfrac{8}{4}\cdot\dfrac{3}{9}=\dfrac{2}{3}\)
Do đó: \(\dfrac{4}{5}\cdot\dfrac{5}{6}=\dfrac{8}{9}:\dfrac{4}{3}\)
c: \(\dfrac{5}{11}\cdot\dfrac{33}{15}=\dfrac{5}{15}\cdot\dfrac{33}{11}=\dfrac{3}{3}=1\)
\(\dfrac{6}{17}\cdot\dfrac{34}{25}=\dfrac{34}{17}\cdot\dfrac{6}{25}=2\cdot\dfrac{6}{25}=\dfrac{12}{25}< 1\)
=>\(\dfrac{5}{11}\cdot\dfrac{33}{15}>\dfrac{6}{17}\cdot\dfrac{34}{25}\)
d: \(\dfrac{15}{19}\cdot\dfrac{38}{5}=\dfrac{15}{5}\cdot\dfrac{38}{19}=3\cdot2=6\)
\(\dfrac{15}{16}:\dfrac{3}{8}=\dfrac{15}{16}\cdot\dfrac{8}{3}=\dfrac{15}{3}\cdot\dfrac{8}{16}=\dfrac{5}{2}\)<6
=>\(\dfrac{15}{19}\cdot\dfrac{38}{5}>\dfrac{15}{16}:\dfrac{3}{8}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a,=3/13.17/29.29/34
=3/13.1/2
=3/26
b,=(4/21+25/42).19/33
=11/14.19/33
=19/42
`a, = 3/13 xx (17/29 xx 29/34)`
`= 3/13 xx 1/2`
`= 3/26`.
`b, = 19/33(4/21 + 25/42)`
`= 19/33 xx ( 33/42 )`
`= 19/42`
![](https://rs.olm.vn/images/avt/0.png?1311)
313×1729)×2934(313×1729)×2934
=313×1729×2934=313×1729×2934
=3×17×2913×29×34=3×17×2913×29×34
=3×17×2913×29×2×17=3×17×2913×29×2×17
=313×2=313×2
=326=326
421×1933+2542×1933421×1933+2542×1933
=1933×(421+2542)=1933×(421+2542)
=1933×(842+2542)=1933×(842+2542)
=1933×3342=1933×3342
=19×3333×42=19×3333×42
=1942
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{3}{7}x\frac{16}{33}+\frac{16}{33}x\frac{4}{7}\)
\(C1:=\frac{16}{77}+\frac{64}{231}=\frac{16}{33}\)
\(C2:=\frac{16}{33}\left(\frac{3}{7}+\frac{4}{7}\right)=\frac{16}{33}.1=\frac{16}{33}\)
học tốt ~~~
C1:3/7×16/33+16/33×4/7
=48/231+64/231
=112/231
C2:3/7×16/33+16/33×4/7
=16/33×(3/7+4/7)
=16/33×7/7
=113/231
![](https://rs.olm.vn/images/avt/0.png?1311)
Cách 1: (Tính bình thường)
= 16/77 + 64/231 (Quy đồng đi nha, mẫu chung là 231)
= 16/33
Cách 2: (Tính nhanh)
= 16/33 x ( 3/7 + 4/7 )
= 16/33 x 1
= 16/33
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\frac{7}{8}=\frac{14}{16}>\frac{11}{16}\)
b) \(\frac{15}{35}=\frac{3}{7}=\frac{24}{56}\)
c) \(\frac{20}{31}>\frac{20}{33}>\frac{19}{33}\)
d) \(\frac{11}{12}<\frac{14}{12}=\frac{7}{6}\)
33/19 x 1/7 - 4/7 x 33/19
= 33/19 x (1/7 - 4/7)
=> không thể tính được nữa vì kết quả sẽ mang số âm (lớp 6 sẽ học)
kết quả số âm = -99/133
33/19x3/7
=99/133